2. YUKON OPEN LOOP GEOEXCHANGE CASE STUDY Na-Cho Nyak Dun First Nation Government House Presented by: Katherine Johnston, EIT EBA Engineering Consultants Ltd.

3. What is Geoexchange?

4. Geoexchange is the coupling of low-grade heat from earth sources (soil, rock, groundwater, surface water, ocean, waste heat) which is transformed using heat pump technology to higher-grade heat for building conditioning, domestic hot water or process purposes.

5. How Does it Work? Heating/ Cooling Load Heat Pump and/or Heat Exchanger Earth Energy Source Return line Loop within building Supply line Ground coupling sideBuilding side

6. How Does it Work? Heating/ Cooling Load Heat Pump and/or Heat Exchanger Earth Energy Source Return line Loop within building Supply line Ground coupling sideBuilding side Our domain

7. Two Types of Ground Heat Exchanger Well Water System (Open Loop) Vertical Borehole System (Closed Loop)

8. Open Loop Well Water System (Open Loop)

9. Location Map – Village of Mayo

10. Village of Mayo “Heart of the Yukon” 407 km north of Whitehorse Population 450 Centre for mineral exploration in the central/ north Yukon Annual “Midnight Marathon” held on the summer solstice

11. Geologic Setting

13. Village of Mayo Wells- History PW -1/ PW-2  Drilled in the 1970’s  Approx. 255 m deep (Drilled Mud Rotary)  15 L/s (“Safe Yields”)  14 ° C (GW Temp)

14. Village of Mayo – Geoexchange History 1987-1988 GSHP commissioned to heat central building group using the existing water distribution system installed in the Village System failure after approximately 1 yr because….

15. Village of Mayo – Geoexchange History Heat pump incompatibility with existing space heating systems Power availability issues related to the Keno Hill Mine (operation until 1989) Failure to account for groundwater quality resulted in severe encrustation/ bio-fouling of the system

16. Village of Mayo – Key Lessons Learned 1)Water quality consideration in system design 2)Need for ongoing monitoring and maintenance

17. Pre-Feasibility Study Results Potential for existence of shallow “perched” aquifer (water supply potential) Potential for existence of deeper “warm” aquifer Need for potable water system regardless Decision to proceed with combined drinking water/ geoexchange supply drilling program

18. NNDFN Building – Expected Drilling Conditions 0 – 100 ftSand, gravel 100 ft – 800 ftSilt/ clay > 800 ftTarget aquifer

21. Village of Mayo – Well Drilling

24. Actual Drilling Conditions 0 – 30 ftSand, gravel 30 ft – 298 ftSilt/ clay 298 ft – 560 ftMedium to coarse sand aquifer

25. Open Loop - Well Screen Design

26. Open Loop – Well Screen Installation

27. Village of Mayo – Well Development

29. Well Chemical Treatment and Testing

32. Hydraulic Testing Results – Constant Rate Test

33. Open Loop – Water Quality Analysis

34. Water Quality Analysis Con’t

35. Key Design Recommendations: Continuous operation of the system Implementation of a regular monitoring and maintenance schedule Use of a single, central heat exchanger Batch chemical injection system upstream of the injection well (CO 2 and Sodium Hypochlorite) to inhibit biological activity and maintain a neutral pH

36. Where are we now? Yukon water license requirements for groundwater extractions above 100 m 3 /day (20 USgpm) First time the Yukon water board is addressing both extraction and re-injection Injection well construction and commissioning will follow water board approval

37. Other Yukon Geoexchange Applications

38. Acknowledgements: Diana M. Allen Broadway Architects DEC Design Quest Engineering Group Na-Cho Nyak Dun First Nation

39. Thank You! Questions? ksjohnston@eba.ca EBA Kelowna 1-250-862-4832